KRISHNACHANDRAN S (1), XU HUANG (2), OH-SUNG KWON (2) and ARUN MENON (3)
(1) Research Scholar, Department of Civil Engineering, IIT Madras, Chennai, India
(2) Post Doctoral Fellow, Department of Civil and Mineral Engineering, University of Toronto, Canada
(2) Professor, Department of Civil and Mineral Engineering, University of Toronto, Canada
(3) Professor, Department of Civil Engineering, IIT Madras, Chennai, India
Seismic analysis requires consideration of bidirectional loading components which have been shown to be more critical compared to unidirectional excitations. Bidirectional loading histories tend to reduce the actual capacity of structural members and accelerate their strength and stiffness degradation. With respect to unreinforced masonry (URM) buildings, bidirectional interaction has been an area in which limited experimental research has been carried out to date. In this regard, no quasi-static tests have been undertaken to study the effect of bidirectional interactions and therefore no loading protocol which represents the failure of URM buildings under bidirectional loading has been established. Hence, the existing numerical models have not been validated for their capacity to capture the interaction response of masonry piers. This study looks at employing the novel testing methodology of pseudo dynamic hybrid simulation to investigate the effect of bidirectional interaction on the response of unreinforced masonry piers. In this approach, the unreinforced masonry pier is modelled analytically in the host computer and experimentally tested simultaneously. The numerical model communicates with the experimental specimen to obtain the unknown response parameters which cannot be characterized by the numerical model independently. Accordingly, the combined numerical-experimental response provides the complete response of the structural member. Results suggest that there is considerable difference between the response of an unreinforced masonry pier under unidirectional and bidirectional loading in terms of strength capacity, stiffness degradation and hysteresis energy dissipation. Also, pseudo dynamic hybrid simulation provides valuable indicators regarding the future course of testing protocols for capturing bidirectional interaction in URM buildings.
KEYWORDS: Unreinforced masonry, Pseudo-dynamic testing, Hybrid simulation, Bidirectional interaction